A variety of systems have been developed for forming various shaped cushion bodies by introducing an initially liquid or creamy material into a system and controlling the material's external environment during an expansion of the material until the material sufficiently cures or sets into its final shape. Foamable synthetic resins, such as polyurethane, are representative of material commonly used in the production of foamed cushion bodies. Amongst these systems, a great deal of work has been carried out in forming large foam buns which, after some initial surface planing, are often sent to locations where the foam bun is further cut and processed into relatively smaller products such as mattress pads, packing material, etc. These foam buns are often formed by injecting the foam material onto an underlying moving sheet which passes through a confining structure such as a pair of opposed side conveyors or a pair of opposed side walls forming a trough like structure. To lessen the friction between the side walls and the rising foam material so as to avoid a higher central area relative to the foam bun's side walls (and thus added waste when squaring off the foam block), the underlying sheet is often curled or bent up along its side edges so as to partially run along the side walls. In addition, many of the foam bun production systems utilize opposing side sheets positioned between the foam and the side walls to reduce friction and in some instances to help pull up the foam on its sides. Examples of foam bun production systems can be seen in U.S. Pat. No. 5,527,172 assigned to Carpenter Company of Richmond, Virginia US, as well as U.S. Pat. Nos. 3,091,811 and 3,906,068.
It is also known in the industry to form foam cushion products in a final state directly by injecting the foam material into a mold whereupon the foam material expands and assumes the shape of the desired product. An example of an automated technique for forming foam cushion products can be seen in U.S. Pat. No. 3,566,448 wherein a pair of horizontally-oriented conveyors comprising a series of partial molds are rotated so as to have the partial molds come into aligned contact shortly after a lower cup shaped mold is partially filled with the liquid foam material. The '448 patent also describes passing sheet material between the molds and foam to keep the molds in a clean state as well as a side shape assistance conveyor.
Other non-automated molding processes using casts or molds have also been used in the industry to form preformed foam packing products which are sent to various manufacturers for use in protecting products being sent out to customers.
The above described prior art systems are not, however, applicable to bag cushion forming and thus fail to provide an automated foam bag cushion production system that can provide formed or shaped foam bag cushions which have inherent benefits such as providing protection from foam contact to products to be shipped and handlers.
There has also been activity in developing automatic cushion bag forming machines such as that represented by U.S. Ser. No. 09/076,087 filed on May 12, 1998, and assigned to Carpenter Company, which is incorporated by reference herein in its entirety, and which describes a method and apparatus for forming sealed foam bag cushions with venting. The individual foam cushions output by the bag forming machine have particular utility in the packing industry in that both the product and the person ib handling the bag can avoid direct contact with the rather sticky foam material.
There has also been utilized heretofore in the industry a foam bag cushion production assembly that includes a foam bag production device having similarities to that described in U.S. Pat. No. 5,679,208 which operates to produce a series of independent, completely sealed (except for venting) foam bag cushions. This foam bag cushion production device is suspended high off the ground so that each of the resultant, independent foam bag cushions drops from the device into a space between a pair of vertically running conveyors and is then brought down to floor level. This system requires an extensive surrounding support network which occupies a great deal of space and is rather cumbersome and complex. In addition, because this system has a film feed structure that imposes an essentially fixed length output, adjustments in bag size are generally limited to height adjustments which relates to the amount of film fed into the bag forming device. Still further, this earlier used system injects a centralized shot of foam material which has to not only expand upward, but also outward to a considerable extent before reaching the side edges of the fixed length bag. This shot positioning is detrimental to high quality foam output both from the standpoint of pouring new foam onto earlier injected foam in a further advanced state of rising and also from the standpoint that foam yield is generally improved when essentially only vertical rising is involved.
The above noted previously relied upon system also does not provide a means for forming particular impressions or protrusions in the resultant foam bag cushion and thus has limited applicability. Also, this earlier used system, in completely forming, sealing, and separating the bag before introduction into the conveyor, represents a system that increases the possibility of earlier developed foam cells being crushed due to the delay in time between when the foam is first input into the bag and when it finally is placed between the vertical conveyors. The complete formation and separation of the bag before introduction into the downstream conveyor system in the prior system, also can lead to a relatively high processing time and thus does not represent a highly efficient system, particularly when considering that many manufacturers desire (but typically cannot satisfy) their foam cushion production output to conform to or coincide with the level of products being produced to be shipped out with foam bag cushion packing. For example, many manufacturers output products at a level which requires in excess of 25,000-50,000 cushions per shift and thus any inefficiency in producing an appropriate number of foam bag cushions is multiplied many times over by the end of the shift.
In the field of preformed and shaped foam cushion molding, a more typical prior art technique for forming shaped foam cushions is wherein foam cushions are produced by placing or dropping a completed, filled and separated bag into a die impression box having a wood die member or the like at the bottom. The cover of the box is then locked shut so that the expanding bag conforms to the contours of the box and the impression die at the bottom of the box. While some systems have been developed placing a plurality of boxes on a turntable so that a previously filled box returns back to a starting point at or closer to the time of completed rising, these systems are still highly labor intensive from, for example, the standpoint of an operator typically having to insert the cushion, close and lock the box, open the box and then remove the cushion. Also, due to the labor intensity and size requirements of such a system, preformed foam cushions are often made off-site and shipped to the product production location requiring large storage requirements and added expense.